<html>
    <head>
        <meta charset="utf-8">
        <title>内容过滤选择器</title>
        <script src="./js/jquery-3.6.0.min.js" type="text/javascript"></script>
        <script>
            $(document).ready(function(){
                $("td:empty").css("background","grey")
            });
        </script>
    </head>
    <body>
        <table id="employees" width="200" border="1">
            <tr><th>ID</th><th>姓名</th><th>性别</th><th>年龄</th><th>学历</th></tr>
            <tr>
                <td>1</td>
                <td>2</td>
                <td>3</td>
                <td>4</td>
                <td>4.</td>
            </tr>
            <tr>
                <td>5</td>
                <td>6</td>
                <td>7</td>
                <td>8</td>
                <td>8.</td>
            </tr>
        </table>
    </body>
</html>